Gas blast electric circuit breaker



y 1942. D. c. PRINCE 7 2,290,207

GASBLAST ELECTRIC CIRCUIT BREAKER Filed July 29, 1941 EXHAUST Inventor: David C. rince, by W His Attorney.

Patented July 21, 1942 GAS BLAST ELECTRIC CIRCUIT BREAKER David 0. Prince, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application July 29, 1941, Serial No. 404,459

6 Claims.

My invention relates to gas blast electric circuit breakers wherein the arc to be interrupted is subjected to a high velocity blast of interrupting gas, such as air, and has for its principal object the provision of an improved gas blast circuit breaker having means for utilizing a high pressure blast supply source economically to supply a maximum amount of interrupting gas to the arc extinguishing device.

It has been proposed to store the gas supply for the interrupting blast in high pressure tanks at 250 pounds per square inch or higher in order to conserve vitally important space in gas blast switching stations, such as urban indoor stations for example. The amount of gas required for a number of consecutive circuit breaker operations within a short time may, however, so drain the supply tank that further operations cannot be relied upon until the compressor equipment has restored the storage tank pressure.

In accordance with my invention, the high pressure blast from the supply tank is utilized so as to supplement the storage tank supply by atmospheric air, thereby making available for are extinguishing purposes a greater supply of gas than stored in the high pressure tank. By this method, there is provided means for increasing the effective capacity of a high pressure storage tank and thereby increasing the possible number of consecutive circuit breaker operations.

My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, the single figure thereof illustrates an elevational view, partly in section, of a cross-blast air circuit breaker embodying the present invention.

There is illustrated by way of example an air circuit breaker of the cross-blast type, although it should be understood that my invention is not limited to this type breaker and may be readily used with other types, such as the wellknown axial blast type wherein the interrupting blast is directed generally longitudinally of the arc stream. The circuit breaker illustrated comprises relatively movable contacts, such as the fixed contact structure I and a coacting movable blade contact 2 separable to form an arc gap in the insulating arc chute structure 3. The breaker terminals to which the contacts are electrically connected are indicated at I and 2' respectively.

The are chute 3 comprises diverging end walls 4 and 5 and more closely spaced parallel side walls 6 and 1 arranged to form a narrow diverging arc extinguishing chamber. The are gap is formed in a slot-like passage 8 at the entrance of the chute through which the blade contact 2 is guided for longitudinal reciprocal movement. The exhaust end of the chute communicates with a pipe or stack 9 for venting the blast gases. A blast supply passage It is formed in the chute opposite the arc passage 8 at one side thereof, and insulating arc extinguishing barriers ll forming gas passages leading to the chute exhaust are positioned adjacent to the arc passage as illustrated at the opposite side thereof. Spaced copper cooling plates I2 are also mounted in the chute in the passages [3 for cooling the highly heated arc gases.

In the arrangement so far described, the are formed in the passage 8 upon separation of the contacts is subjected to a transverse blast of gas from the passage Ill. This drives the are against the barriers I! and into the passages [3 where it is extinguished. A gas blast circuit breaker of this character is disclosed and claimed in an application Serial No. 303,126, filed November 6, 1939 by D. C. Prince et al. for Circuit breaking apparatus and method of operating the same, and assigned to the same assignee as the present invention.

The blast supply pressure is preferably high, such as from pounds to 250 pounds per square inch, and need be applied but a very short time since the arc is extinguished in this type breaker generally within one or two half cycles of arcing. For the purpose of supplementing the high pressure tank supply, I provide means such as aspirator or injector means, for drawing atmospheric air into the blast supply passage Ill along with the high velocity blast from the storage tank. In the specific arrangement shown, the storage tank [4, which may be supplied by compressor equipment, or the like, (not shown) with an interrupting gas at any suitable pressure, is provided with a blast control valve l5 operable in any suitable manner as indicated at IE to admit the blast to the conduit l 5. The blast valve is normally biased closed by a spring E5".

The conduit l6 terminates in a nozzle device I! of Venturi shape positioned within a flared concentric nozzle extension it of the passage l0 so as to constitute an aspirator for drawing atmospheric air into the annular passage H) as indibated by the flow direction arrows. The blast, which is directed through the nozzle I! b opening of the valve l5 upon separation of the contacts is, as previously stated, under high pressure and the high velocity jet flowing through the passage I0 is effective to cause by induction flow of an appreciable amount of atmospheric air also into the passage [0 and into the arc extinguishing chamber where it aids interruption of the are.

Where conservation of space is particularly important, the storage tank pressure can be increased and the size of the tank decreased since the resulting high velocity blast is more eifective in drawing into the blast passage a larger amount of supplementary air. Furthermore, there is no appreciable energy loss at the aspirator as in the case of certain metering devices. Th high pressure gas blast itself expands providing a greater volume at lower pressure for the arc chute, and to this is added the entrained air drawn into the nozzle I8. Accordingly, it is possible to employ a smaller amount of high pressure gas to obtain the same beneficial result in interrupting ability as well as cooling and oxidizing the hot arc chute gases.

Under certain conditions, comparatively expensive gases having good arc extinguishing characteristics may be specified. In such cases, as in the case of CO2, the gas may be very highly compressed or even in liquid form so that storage cylinders of comparatively small size may be used. This gas can then be directed to the aspirator at l'l-l8 where it is supplemented by atmospheric air. Accordingly, a smaller amount of the more expensive gas stored under high pressure can be used due to the additional supply of air, which in itself is known to be a good are extinguishing agent.

Also, in installations of this character reducing valves between the high pressure storage tank and breaker can be omitted and thereby the blast gas supply more efiiciently used. That is, instead of Wasting potential gas supply by dropping the pressure to the pressure best utilized at the arc chute through a reducing valve, I provide means tending to conserve this energy since there is available in the arc chute an increased volume (of gas and air) roughly inversely proportional to the reduction in pressure through the aspirator.

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

' What I claim as new and desire to secure by Letters Patent of the United States is:

l. A gas blast circuit breaker having contacts separable to form an arc gap, a source of interrupting gas under pressure, means for directing a blast of gas from said source to said are gap to extinguish arcing, and means for supplementing said gas blast by atmospheric air independent of said source, said atmospheric air being directed to said arc gap in accordance with the operation of said gas blast.

2. A gas blast circuit breaker having contacts separable to form an arc gap, a source of interrupting gas under pressure, means for directing a blast of gas from said source to said arc gap to extinguish arcing, and induction means for drawing atmospheric air to said are gap to supplement said gas blast.

3. A gas blast circuit breaker having contacts separable to form an arc gap, arc extinguishing structure adjacent to said arc gap, a source of interrupting gas under high pressure, means including a conduit for directing a blast of gas from said source to said are extinguishing structure to traverse said are gap, and induction means associated with said conduit for supplementing said gas blast by atmospheric air, said atmospheric air being directed to said are gap in accordance with the operation of said gas blast.

4. A gas blast circuit breaker having contacts separable to form an arc gap, a source of interrupting gas under pressure, means for directing a blast of gas from said source to said arc gap to extinguish arcing, and an aspirator located between said source and arc gap for causing atmospheric air in addition to said gas blast to be directed to said gap.

5. A gas blast circuit breaker having contacts separable to form an arc gap, a source of interrupting gas under high pressure, means including a conduit and an aspirator for directing a blast of gas from said source to said are to extinguish arcing, said aspirator supplementing the function of said gas blast by drawing in atmospheric air, said atmospheric air being directed to said arc gap in accordance with the operation of said gas blast so that the volume of the combined gas and air supplied to the arc gap space is increased as the gas pressure is decreased.

6. A gas blast circuit breaker comprising an insulating arc chute, contacts separable to form an arc gap at the entrance of said chute, a source of interrupting gas under pressure, means including a conduit for directing a'blast of gas from said source to the entrance of said chute and to said are gap to extinguish arcing, and means associated with said conduit for supplementing said gas blast by atmospheric air independent of said source including a pair of concentrically disposed nozzles constituting an aspirator, said atmospheric air being directed to said arc gap through one of said nozzles in accordance with passage of said gas blast through the other nozzle.

DAVID C. PRINCE. 

